Strainer



L. P. HOFF May 30, 1933.

S TRAI NER Filed Sept. 25, 1950 Patented May 30, 1933 UNETED STATESPATENToFFIcs LEIGH P. norr, or BALA-CYNWYD', PENNSYLVANIA, AssienoR TOTHE ALLEN}- SHERMAN-HOFF COMPANY, A CORPORATION or PENNSYLVANIA STRAINERApplication filed September 25, '1930. Serial No. 484,307.

This invention relates to strainers, and more particularly to selfcleaning strainers adapted to prevent the entry of foreign material intofluid pumps and the like.

In a large number of industrial operations it is necessary. to pumpwater or other liquids containing a certain amount of solid abrasivematerial. Pumps have beendesigned which are especially suited forpumping liquid con 1 taining ash or other abrasive material if theparticles of material are not of too great size. It therefore becomesnecessary to provide some means of preventing particles of solidmaterial greater than a certain size from entering the pump. Aparticular instance where my strainer .is very advantageous is in arecirculating ash disposal system for a boilerfurnace. In this systemwater under high pressure is discharged through jets or nozzles and theash from the furnace is carried to a sump by the water so discharged.The sump is provided with a number of baflies which accomplish a partialseparation of water and ash and the 2 separated water passes into abaflled ofi' portion of the sump from which it isdrawn by a highpressure piunp and again discharged through the nozzles.

Although the water and ash may be fairly well separated in the sump, itis important that a strainer be provided in the intake of the highpressure pump to prevent particles of ash from entering the pump andcausing excessive wear both onthe pump and the nozzles. The straineralso eliminates the danger of clogging the nozzles and the smallclearance spaces of the pump.

It is among the objects of my invention, therefore, to provide astrainer particularly adapted for use in the above described apparatus.

A further object of my invention is to provide a strainer adapted to befitted into the intake pipe of a pump which will prevent large particlesof solid material from en tering thepump.

Another object is the provision of a self cleaning strainer which isautomatic in operation for preventing large particles of'solid materialfrom entering a pump.

Another object ofmy invention is the provision of a strainer which is ofsimple construction and which may be economically manufactured and isparticularly adapted to easy renewal'of the wearing parts.

Other objects of my invention will appear from the following descriptionof one form thereof, reference being had to the accompanying drawing inwhich:

Fig. lis a sectional side elevation illus- 6'0 trating my strainer inposition in the intake pipe or pump;

Fig. 2 is a plan section taken on the line, 2-2 of Fig. 1; Fig. 3 is adetached perspective view the screen carrying cage and screen;

Fig. 4 illustrates theposition of the screen when water is being pumped;1

Fig. 5 illustrates the position thefscreen assumes when the pump stops,and water it flows back through the strainer. I

The body of my strainer is made up of an outer cylindrical shell 1having a flange 2 at its top. A removable cover plate 3 is secured inplace on the top of the shell 1 by the bolts 4. On one side of the shell1 is secured a short section of pipe 5 which form'sthe outlet from thestrainer. This pipe 5 isconnected to the pump intake pipe 6. A ring 7 isse cured in place on the inner surface of the shell 86- 1 at a pointsomewhat below'the outlet openbe drawn up to the screen 9 and the waterwill 7 pass out-throughthe outletopening 8 to the pump while most ofthesolid matter will be held'back bythe screen. When water is flow ingthrough the screen to the pump, the centerpart of the screen 9 will bebent upwardly, as best seen in Fig. 4, by the action of the r waterflowing upwardly through it and the 1% this bending action will free anysmall partipressure of the solid material on its under side. As theoutlet opening 8 is above the screen 9, when the pump is stopped thewater in the intake pipe 6 and in the upper portion of the strainerhousing 1 will flow back down through the screen 9 and flush the solidmaterial collected on the under side ofthe screen back into the sump.This back flow will also bend thescreen downwardly to ap proximately theposition shown in Fi 5 and cles of material which may have become lodgedin the mesh of the screen.

The upper end of the screen cage 10 isadapted to abut against the topcover plate 25 and serves to hold the screen 9 down in posi' tionagainst the upward pressure of material on its under side when the pumpis operating. This basket also serves as a convenient handle with whichto remove the screen when it is desired to change the size of the screenmesh.

It will be noted that the area of the screen 9 in the housing 1 is largecompared to that of the outlet pipe 6. Thus the flow through the screenwill be relatively slow and wear will be reduced to a minimum. Thisconstruction also greatly reduces the power required to draw the liquidthrough the strainer.

If desired the screen 9 maybe made rigid instead of flexible asillustrated and the strainer will still be substantially self cleaningdue to the back flow of water therethrough.

From the above description it will be seen that my improved strainer isparticularly adapted to be used with pumps which are designed forpumping water carrying solid material. As above explained, my straineris self cleaning and therefore eliminates the necessity of providing ahand hole for manually cleaning the screen of the strainer at more orless frequent intervals.

Although I have shown and described a preferred form of my invention, itwill be seen by those skilled in the art that modifications andvariations thereof may be made without departing from the spirit of myinvention. I do not therefore, limit myself to the precise details shownand described, but claim as my invention, all embodiments thereof,coming within the scope'of the appended claims.

I claim: v

1. A strainer comprising an outer shell having a bottom inletopening'and an outlet opening on one side, aremovable closure for thetop of said shell, a flexible screen disposed within said shell at apoint'below said outlet opening and means for maintaining the peripheryof said screen. in fixed relation to the walls of said shell, whilepermitting movement of the central portion ofsaid screen in a directionparallel to the path of material passing through the strainer.

2. A self cleaning strainer comprising a casing having vertically spacedinlet and discharge openings, said inlet opening being be low saiddischarge opening, a flexible screen extending across said casingbetween said inlet and discharge openings, and means for maintaining theperipheryl of said screen stationary relative to said housing whilepermitting the central portion of said screen to move vertically.

3. In a strainer, the combination of a housing having vertically spacedinlet and outlet openings, said outlet opening being disposed above saidinlet opening, and a screen adapted to bend upwardly in its centralportion when material is passing throughsaid housing from said inlet tosaid outlet, and to bend downwardly when material is passing throughsaidhousing from said outlet to said inlet. I i

1. A self cleaning strainer for mixtures of liquid and solid abrasivematerial comprising, a casing having vertically spaced inlet anddischarge openings, said inlet opening being below said dischargeopening, a flexible screen extending across said casing between saidinlet and'discharge openings, and means for maintaining the periphery ofsaid screen stationary relative to said housing while per mitting thecentral portion of said screen to move vertically, said screen beingadapted to be flexed upwardly by flow of the mixture from said inlet tosaid discharge opening and to be flexed downwardly when said flow fromLEIGH P. HOFF.

